# Spin-phonon coupling in hole-doped pyrochlore iridates Y$_2$(Ir$_{1-x}$Ru$_x$)$_2$O$_7$: A Raman scattering study

## TL;DR

This study investigates the spin-phonon coupling in doped pyrochlore iridates Y$_2$(Ir$_{1-x}$Ru$_x$)$_2$O$_7$ using temperature-dependent Raman scattering, revealing anomalous phonon behavior linked to magnetic transitions and doping effects.

## Contribution

It provides the first detailed Raman scattering analysis of spin-phonon coupling in doped pyrochlore iridates, highlighting how magnetic ordering influences lattice vibrations.

## Key findings

- Magnetic transition temperature decreases with Ru doping.
- Anomalous shifts in Raman modes occur around magnetic transition temperatures.
- Strong deviation from anharmonic decay in Raman mode frequency indicates spin-phonon coupling.

## Abstract

Temperature dependent Raman scattering measurements have been performed to explore unusual coupling between magnetism and crystal structure in doped pyrochlore iridate Y$_2$(Ir$_{1-x}$Ru$_x$)$_2$O$_7$ with $x$ = 0.0, 0.05 and 0.2. The parent Y$_2$Ir$_2$O$_7$ shows an onset of magnetic ordering around $\sim$ 160 K ($T_{N}$) which monotonically decreases with Ru doping. Further, magnetic moment also decreases with progressive substitution of Ru. Substitution of Ru$^{4+}$ (4$d^4$) for Ir$^{4+}$ (5$d^5$) does not introduce significant modification in structural parameters, however, the magnetic transition temperature decreases systematically with doping. Raman scattering data show an anomalous change in $A_{1g}$ and $P_3$ Raman mode frequency and line-width across $T_{N}$ of individual samples. We further show that the shifting of Raman mode frequency with temperature exhibits a strong deviation from anharmonic decay around and below the $T_{N}$ of respective samples which underlines a spin-phonon coupling in these materials.